Although there is considerable evidence that estradiol, testosterone and oxandrolone augment growth hormone (GH) secretion, the mechanism(s) responsible are not known. We hypothesize that sex steroids increase the sensitivity of the somatotroph to the physiologic GH secretogogue, growth hormone releasing hormone (GHRH). We plan to compare the GH response to exogenous GHRH before and after estradiol, testosterone, oxandrolone or placebo in pre-pubertal children.